This invention relates to flow machines, such as turbines or the like, and is particularly directed to means for locking the rotor blades with respect to circumferential movement in a circumferential slot in the rim of the rotor disk of the flow machine.
In accordance with known practice, the rotor of a flow machine is provided with a circumferentially extending slot, the rotor blades of the machine being locked, with respect to radial movement, in the circumferential slot. For this purpose, the circumferential slot may have laterally projecting flanks. A blade stacking hole is provided in the circumferential slot, in order to enable insertion of the roots of the rotor blades into the circumferential slot, the rotor blades then being circumferentially slidable away from the blade stacking hole. In such arrangements the blade stacking hole has been closed by a blade stop member after the rotor blades have been closely stacked together in the circumferential slot for installation. Such a stop member, in accordance with prior practice comprises a number of parts shaped to suit the differentiated blade pitch of the blades, and also to suit the specific type of blade mounting employed in the machine, taking into consideration such factors as the shape of the slot, and the configuration of the pedestal of the blade.
In such installations, the multi-part blade stop member is generally riveted or wedged to the rim of the rotor.
The assembly of rotor blades on a rotor in such arrangements has proven to be time consuming and expensive in mass production. In addition, the disassembly of the rotor blades, for example, for replacement of the blades, required a substantial amount of work, and was an expensive procedure.
Another drawback of the prior art blade stoppers is seen in their relatively large size which could not only result in an unbalance of the rotor disk or of the entire rotor of the flow machine, but which could also cause a rather critical reduction in the thickness of the rim material near the stacking hole in the rotor.
British Pat. No. 903,176 discloses an arrangement aiming at solving such problems. The known blade locking arrangement of this British Patent locks the blades in the circumferential direction by means of a blade stopper, which may be pressed down against a coil spring through the blade stacking hole for insertion into the circumferential slot. Within the blade stacking hole, the locking element is allowed to spring back sufficiently between the last and the next to last blades, to prevent its displacement circumferentially between the laterally projecting flanks of the circumferential slot of the rotor. This known arrangement thus provides a blade locking means which substantially eliminates the need for making the rim material thinner. However, the known blade locking device is not anchored exactly between or with the two end blades in the locked operating position. During displacement of the locking device within the circumferential groove or slot the blade stopper is also not exactly guided, so that it is not easily displaceable circumferentially, whereby assembly and disassembly of the known device is difficult.